This application is directed to an improved embodiment of what is known in the art as a B.R.D.A. former, with which applicants are familiar. B.R.D.A. are the initials of Boxboard Research and Development Association of Kalamazoo, Mich.
It has been known to make paper on a perforated cylinder revolving in a vat. In the above mentioned B.R.D.A. former a perforated cylinder is still used, but the vat is eliminated in favor of the flow box having a pressure lid in contact with about eight inches of the cylinder mold face. The stock is collected on the face of the mold with most of the water draining through its wire face. It is most important that the fibrous component of the paper making stock be evenly dispersed with random fiber networks and no streaking or streaming or bulges in the lid. It is also important that the stock be free of local turbulence which could cause non-uniformities in the weight, thickness and appearance of the finished paper. The B.R.D.A. former utilizes a tapered flow spreader delivering stock to a set of elongated plastic tubes which enter the explosion chamber at cross angles to each other and at oblique angles to the floor of the chambr and to the face of the upstanding baffle in the chamber, all as disclosed in U.S. Pat. No. 3,565,758 of Feb. 23, 1971 and U.S. Pat. No. 3,622,450 of Nov. 23, 1971 of St. Anne's Board Mill Company Ltd., Bristol, England.
It has heretofore been proposed in U.S. Pat. No. 2,894,581 to Goumeniouk of July 14, 1959 and U.S. Pat. No. 3,328,236 to Burgess of June 27, 1967 to provide a tapered manifold of circular, or rectangular cross section which feeds stock directly to a head box by means of a bank of elongated crossed tubes. As mentioned above it has also been proposed to provide a similar tapered manifold and a bank of shorter crossed tubes to feed stock into an expansion chamber and thence into a pressure lid as in the B.R.D.A. apparatus. It has further been proposed in U.S. Pat. No. 2,929,449 to Mardon of Mar. 22, 1960 and U.S. Pat. No. 3,119,733 to Wilson of Jan. 28, 1964 to provide a tapered manifold of rectangular cross section which has an apertured plate as one wall for delivering stock through the apertures directly into a head box.